The feature I wish google docs had:

A "system prompt" where you tell things to look for and highlight in your document, and which runs continuously in the background.

It would be like Grammarly, but for the things *you* care about.

E.g.:
"use 'following' instead of 'below' to refer to parts of the doc"
"make sure problem names are capitalized"
"make sure all problems have examples"
"make sure all problems are numbered and have increasing numbers"